Backlinks: definition and AI search relevance

A backlink is a hyperlink on a page you don't own that points to a page you do. If a trade publication links to your pricing page, that link is a backlink for you and an outbound link for them.

Three terms travel with it:

• Inbound link is a synonym.
• Link building is the practice of earning or placing backlinks.
• An unlinked mention names your brand without linking to you. It matters more for AI answers than most link-building plans assume.

Crawlers follow links to discover pages, so a backlink can lead a search engine to a URL it hadn't found. In classic search, links have long been treated as one input among many.

Most link metrics you see come from SEO vendors, not engines. Domain Authority is a Moz metric. Domain Rating is an Ahrefs metric. Both are regressions built from backlinks and traffic. No search or AI engine computes them, and Google publishes no site-level authority score. Treat them as vendor estimates, not as anything an engine reads.

The path from a backlink to an AI answer is indirect, and every step is uncertain.

1. Links may help a page rank in classic search.
2. Ranking partly overlaps with AI citations. Ahrefs found that 37.9% of URLs cited in AI Overviews also appeared in the first 10 results (March 2026). The rest came from lower positions.
3. Retrieval is per query, and engines rewrite queries before searching, so no rank guarantees a page enters the answer.

Then there's the confounder. Researchers found that the top 20 news sources accounted for 67.3% of OpenAI models' citations (arXiv 2507.05301, data from March to May 2025). Large, well-known brands earn many links and many citations. No study controls for brand size, because the usual controls are link metrics, which are proxies for brand size itself.

What to do instead

When engines cite other sites for your category, being named on those sites is the route into the answer. That's an association, not a guarantee. Find which pages the engines cite for your buyer questions, then work to be listed, reviewed or described accurately there. Fix access first: an engine can't cite a page its crawlers can't fetch. For the longer argument, read whether backlinks still matter for AI search.

• "More backlinks get you cited by AI." No engine documents this. Google says pages need to be indexed and eligible for a snippet to appear in AI Overviews or AI Mode, with "no additional technical requirements" (digest of Google's AI features docs).
• "Build domain authority for AI." There is no engine-side authority score to build. The number belongs to a vendor.
• "Links help the model remember you." Retrieval-off answers come from training data frozen at a cutoff. Nothing shows links change that this quarter.
• "Backlinks are worthless now." That isn't supported either. They still matter to classic search, which still feeds Google's AI surfaces. See whether SEO is still relevant with AI answers.

• Unlinked mention: your brand named without a link.
• Topical relevance: one of the few factors several GEO studies agree on.
• Navigational link: the plain link ChatGPT can show even when a site opts out of search.
• Training data: what the model learned before its cutoff.

Is a nofollow or sponsored link still a backlink? Yes. Any link from another site to yours is a backlink, whatever attributes it carries. The attribute tells search engines how the linking site wants the link treated. For AI answers, the more useful question is whether the page itself is one that engines cite for your topic, and whether it names you accurately.

Do AI crawlers follow backlinks to find my site? Crawlers discover URLs partly by following links, so a link can surface a page. Discovery isn't access, though. Your robots.txt must allow each retrieval bot, such as OAI-SearchBot for ChatGPT search, and your firewall or CDN must not return a 403. Your key content also needs to be in the HTML before JavaScript runs.

Should I stop link building? Not because of AI. Links still play a role in classic search, and Google's AI surfaces draw on Google's index. Just stop justifying link building as an AI citation tactic. Put AI-specific effort into crawler access and into being named accurately on the pages engines already cite.

How do I find which sites AI engines cite for my category? Ask the engines the questions your buyers ask and record the cited sources, platform by platform. Answers vary by engine and by query, so one test is a sample. The free checker on this site runs up to three buyer questions as a snapshot, which is a reasonable first look.